High-energy γ rays of cosmic origin

1968 ◽  
Vol 46 (10) ◽  
pp. S484-S487 ◽  
Author(s):  
K. C. Anand ◽  
R. R. Daniel ◽  
S. A. Stephens
Keyword(s):  
Cosmic Ray ◽  
High Energy ◽  
X Rays ◽  
Inverse Compton Scattering ◽  
Upper Limits ◽  
Inverse Compton ◽  
Geomagnetic Cutoff ◽  
Γ Rays ◽  
Residual Air ◽  
Cosmic Origin

A stack of nuclear emulsions flown over Hyderabad (vertical geomagnetic cutoff rigidity 16.9 GV), India, under 6 g/cm2 of residual air has been used to set upper limits to the flux of γ rays of cosmic origin. The integral flux values obtained are 13 × 10−4, 6 × 10−4, 2.6 × 10−4, 1.4 × 10−4, 0.6 × 10−4, and 0.3 × 10−4 photons (em2 s sr)−1 for energies greater than 50 MeV, 100 MeV, 2 GeV, 5 GeV, 10 GeV, and 50 GeV respectively. Using these data and those of Kraushaar et al. (1965), it seems unlikely that cosmic-ray collisions in meta-galactic space can be an important source of electrons needed to explain the finite flux of cosmic X rays as due to the inverse Compton scattering of these electrons with photons of the universal blackbody radiation at 3 °K; such collisions would predict a flux of γ rays much in excess of the upper limits obtained in the energy region 50–100 MeV.

Can Galactic γ-Ray Background be due to Superposition of γ-Rays from Millisecond Pulsars?

1998 ◽  
Vol 188 ◽  
pp. 273-274
Author(s):  
V.B. Bhatia ◽  
S. Mishra ◽  
N. Panchapakesan
Keyword(s):  
Cosmic Rays ◽  
Cosmic Ray ◽  
Diffuse Radiation ◽  
High Energy ◽  
Molecular Gas ◽  
Inverse Compton Scattering ◽  
High Energy Electrons ◽  
Inverse Compton ◽  
Γ Rays ◽  
Γ Ray

The SAS 2 and COS B observations have established the existence of diffuse γ-rays in our Galaxy in various energy ranges. The diffuse radiation is attributed to the interaction of cosmic ray nuclei and electrons with the particles of interstellar atomic and molecular gas (via the decay of pions and bremsstrahlung, respectively). Inverse Compton scattering of interstellar photons by the high energy electrons of cosmic rays may also be contributing to this background. In addition some contribution may come from discrete sources of γ-rays.

scholarly journals Very High Energy γ-Ray Generation Near The Light Cylinder of an Axisymmetric Rotator: Cos-B Like γ-Ray Sources

1992 ◽  
Vol 128 ◽  
pp. 207-208
Author(s):  
S. V. Bogovalov ◽  
YU. D. Kotov
Keyword(s):  
High Energy ◽  
Relativistic Electrons ◽  
X Rays ◽  
Inverse Compton Scattering ◽  
Light Cylinder ◽  
Radiation Spectra ◽  
Inverse Compton ◽  
Very High Energy ◽  
Γ Ray ◽  
Very High

AbstractSuper-hard γ-ray radiation spectra have been calculated. This radiation is generated near the velocity-of-light cylinder through the process of inverse-Compton scattering of relativistic electrons by thermal photons radiated by a neutron star. These calculations have been compared with observations of the Crab and Vela pulsars at 1000-GeV γ-ray energies. A correlation between γ-ray flares and those in soft (Ex ≃ lkeV) X-rays are predicted.

scholarly journals Particle Acceleration in Extragalactic Jets and Implications for the High-Energy Emission from Blazars

1994 ◽  
Vol 159 ◽  
pp. 29-32
Author(s):  
R. Schlickeiser ◽  
C. D. Dermer
Keyword(s):  
Compton Scattering ◽  
Accretion Disk ◽  
High Energy ◽  
Relativistic Electrons ◽  
Spectral Evolution ◽  
Inverse Compton Scattering ◽  
Central Engine ◽  
Inverse Compton ◽  
Γ Rays ◽  
Γ Ray

We demonstrate that the prevalence of superluminal sources in the sample of γ-ray blazars and the peak of their luminosity spectra at γ-ray energies can be readily explained if the γ-rays result from the inverse Compton scattering of the accretion disk radiation by relativistic electrons in outflowing plasam jets. Compton scattering of external radiation by nonthermal particles in blazar jets is dominated by accretion disk photons rather than scattered radiation to distances of ∼ 0.01–0.1 pc from the central engine for standard parameters. The size of the γ-ray photosphere and the spectral evolution of the relativistic electron spectra constrain the location of the acceleration and emission sites in these objects.

scholarly journals Starburst and post-starburst high-redshift protogalaxies

2019 ◽  
Vol 626 ◽  
pp. A85 ◽  
Author(s):  
Ellis R. Owen ◽  
Kinwah Wu ◽  
Xiangyu Jin ◽  
Pooja Surajbali ◽  
Noriko Kataoka
Keyword(s):  
Star Formation ◽  
High Redshift ◽  
High Energy ◽  
Starburst Galaxies ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
High Energy Cosmic Rays ◽  
Radiation Fields ◽  
Inverse Compton

Quenching of star-formation has been identified in many starburst and post-starburst galaxies, indicating burst-like star-formation histories (SFH) in the primordial Universe. Galaxies undergoing violent episodes of star-formation are expected to be rich in high energy cosmic rays (CRs). We have investigated the role of these CRs in such environments, particularly how they could contribute to this burst-like SFH via quenching and feedback. These high energy particles interact with the baryon and radiation fields of their host via hadronic processes to produce secondary leptons. The secondary particles then also interact with ambient radiation fields to generate X-rays through inverse-Compton scattering. In addition, they can thermalise directly with the semi-ionised medium via Coulomb processes. Heating at a rate of ∼10−25 erg cm−3 s−1can be attained by Coulomb processes in a star-forming galaxy with one core-collapse SN event per decade, and this is sufficient to cause quenching of star-formation. At high-redshift, a substantial amount of CR secondary electron energy can be diverted into inverse-Compton X-ray emission. This yields an X-ray luminosity of above 1041 erg s−1by redshiftz = 7 which drives a further heating effect, operating over larger scales. This would be able to halt inflowing cold gas filaments, strangulating subsequent star-formation. We selected a sample of 16 starburst and post-starburst galaxies at 7 ≲ z ≲ 9 and determine the star-formation rates they could have sustained. We applied a model with CR injection, propagation and heating to calculate energy deposition rates in these 16 sources. Our calculations show that CR feedback cannot be neglected as it has the strength to suppress star-formation in these systems. We also show that their currently observed quiescence is consistent with the suffocation of cold inflows, probably by a combination of X-ray and CR heating.

scholarly journals THE FSRQs 3C 279 AND PKS 1510-089: MAGIC LATEST RESULTS AND MULTIWAVELENGTH OBSERVATIONS

2014 ◽  
Vol 28 ◽  
pp. 1460176 ◽  
Author(s):  
◽  
G. DE CANEVA ◽  
U. BARRES DE ALMEIDA ◽  
E. LINDFORS ◽  
K. SAITO ◽  
...  
Keyword(s):  
Spectral Energy Distribution ◽  
High Energy ◽  
Spectral Energy ◽  
X Rays ◽  
Spectrum Radio ◽  
Upper Limits ◽  
Very High Energy ◽  
Γ Rays ◽  
Differential Flux ◽  
Multiwavelength Observations

At very high energy (VHE, E> 100 GeV), we count only three blazars of the flat spectrum radio quasars (FSRQs) type to date. The MAGIC experiment detected all three of them; here we present MAGIC observations of 3C 279 and PKS 1510-089. 3C 279 was observed in 2011, without a significant detection, hence upper limits on the differential flux have been computed. The MAGIC observations of PKS 1510-089 in 2012 were triggered by alerts of high activity states and resulted in a significant detection. MAGIC observations are complemented with simultaneous multiwavelength observations in high energy γ rays, X-rays, optical and radio wavelengths and polarization measurements. With the study of the spectral features and the variability observed, we aim to identify the physical processes responsible for the behavior of this source class. In particular, we propose coherent scenarios, which take into account both the modeling of the spectral energy distribution and the constraints obtained from the lightcurves.

scholarly journals Inverse-Compton scattering in the resolved jet of the high-redshift quasar PKS J1421−0643

2020 ◽  
Vol 497 (1) ◽  
pp. 988-1000 ◽  
Author(s):  
D M Worrall ◽  
M Birkinshaw ◽  
H L Marshall ◽  
D A Schwartz ◽  
A Siemiginowska ◽  
...  
Keyword(s):  
Gamma Ray ◽  
High Redshift ◽  
Lorentz Factor ◽  
High Energy ◽  
Radio Spectrum ◽  
X Rays ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Jet Power

ABSTRACT Despite the fact that kpc-scale inverse-Compton (iC) scattering of cosmic microwave background (CMB) photons into the X-ray band is mandated, proof of detection in resolved quasar jets is often insecure. High redshift provides favourable conditions due to the increased energy density of the CMB, and it allows constraints to be placed on the radio synchrotron-emitting electron component at high energies that are otherwise inaccessible. We present new X-ray, optical, and radio results from Chandra, HST, and the VLA for the core and resolved jet in the z = 3.69 quasar PKS J1421−0643. The X-ray jet extends for about 4.5 arcsec (32 kpc projected length). The jet’s radio spectrum is abnormally steep and consistent with electrons being accelerated to a maximum Lorentz factor of about 5000. Results argue in favour of the detection of iC X-rays for modest magnetic field strength of a few nT, Doppler factor of about 4, and viewing angle of about 15°, and predict the jet to be largely invisible in most other spectral bands including the far- and mid-infrared and high-energy gamma-ray. The jet power is estimated to be about 3 × 1046 erg s−1 which is of order a tenth of the quasar bolometric power, for an electron–positron jet. The jet radiative power is only about 0.07 per cent of the jet power, with a smaller radiated power ratio if the jet contains heavy particles, so most of the jet power is available for heating the intergalactic medium.

Predictions of inverse Compton radiation from PSR B1259–63

2000 ◽  
Vol 177 ◽  
pp. 531-532
Author(s):  
J. G. Kirk ◽  
Lewis Ball ◽  
O. Skjæraasen
Keyword(s):  
Synchrotron Radiation ◽  
Delta Function ◽  
Companion Paper ◽  
High Energy ◽  
Termination Shock ◽  
Relativistic Electrons ◽  
X Rays ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Function Approximations

Unpulsed high energy (TeV) emission has been detected from several isolated pulsars (Aharonian 1999) and presumably results from relativistic electrons accelerated at the termination shock of an MHD wind driven by the pulsar itself. These electrons inverse Compton scatter target photons from either the cosmic microwave background, or from their own synchrotron radiation.The rotation-powered binary pulsar PSR B1259–63 (Johnston et al. 1996) is also thought to drive an MHD wind, and the synchrotron radiation of electrons accelerated at its termination shock is probably the source of the unpulsed X-rays seen from this object by ROSAT, OSSE and ASCA (Tavani & Arons 1997). Compared to the isolated pulsars, however, the the pulsar’s Be-star companion provides an energy density of target photons available for inverse Compton scattering which is some 11 orders of magnitude larger. Using delta-function approximations to the emissivities and a monochromatic approximation to the spectrum of the target photons, we modelled the observed X-ray synchrotron emission and predicted the TeV emission in a recent paper (Kirk et al. 1999). In this contribution we improve these calculations in two respects – by treating the target spectrum more precisely, as described in the companion paper (Ball & Kirk 1999), and by relaxing the approximations made in the emissivities.

scholarly journals Suzaku observation of Jupiter’s X-rays around solar maximum

2019 ◽  
Vol 71 (5) ◽  
Author(s):  
Masaki Numazawa ◽  
Yuichiro Ezoe ◽  
Kumi Ishikawa ◽  
Takaya Ohashi ◽  
Yoshizumi Miyoshi ◽  
...  
Keyword(s):  
Solar Activity ◽  
Compton Scattering ◽  
High Energy ◽  
Spectral Studies ◽  
Relativistic Electrons ◽  
X Rays ◽  
Diffuse Emission ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton

Abstract We report on results of imaging and spectral studies of X-ray emission from Jupiter observed by Suzaku. In 2006, Suzaku found diffuse X-ray emission in 1–5 keV associated with Jovian inner radiation belts. It has been suggested that the emission is caused by the inverse-Compton scattering by ultra-relativistic electrons (∼50 MeV) in Jupiter’s magnetosphere. To confirm the existence of this emission and to understand its relation to the solar activity, we conducted an additional Suzaku observation in 2014 around the maximum of the 24th solar cycle. As a result, we successfully found the diffuse emission around Jupiter in 1–5 keV again, and also found point-like emission in 0.4–1 keV. The luminosity of the point-like emission, which was probably composed of solar X-ray scattering, charge exchange, or auroral bremsstrahlung emission, increased by a factor of ∼5 with respect to the findings from 2006, most likely due to an increase of the solar activity. The diffuse emission spectrum in the 1–5 keV band was well-fitted with a flat power-law function (Γ = 1.4 ± 0.1) as in the past observation, which supported the inverse-Compton scattering hypothesis. However, its spatial distribution changed from ∼12 × 4 Jovian radius (Rj) to ∼20 × 7 Rj. The luminosity of the diffuse emission increased by the smaller factor of ∼3. This indicates that the diffuse emission is not simply responding to the solar activity, which is also known to cause little effect on the distribution of high-energy electrons around Jupiter. Further sensitive study of the spatial and spectral distributions of the diffuse hard X-ray emission is important to understand how high-energy particles are accelerated in Jupiter’s magnetosphere.

scholarly journals EMISSION FROM LARGE-SCALE JETS IN QUASARS

2008 ◽  
Vol 17 (09) ◽  
pp. 1475-1481 ◽  
Author(s):  
YASUNOBU UCHIYAMA
Keyword(s):  
Large Scale ◽  
Gamma Ray ◽  
High Energy ◽  
X Rays ◽  
Microwave Background ◽  
Electron Population ◽  
Inverse Compton Scattering ◽  
Relativistic Jet ◽  
Inverse Compton ◽  
Quasar Jets

We consider the emission processes in the large-scale jets of powerful quasars based on the results obtained with the VLA, Spitzer, Hubble, and Chandra. We show that two archetypal jets, 3C 273 and PKS 1136–135, have two distinct spectral components on large-scales: (1) the low-energy (LE) synchrotron spectrum extending from radio to infrared, and (2) the high-energy (HE) component arising from optical and extending to X-rays. The X-ray emission in quasar jets is often attributed to inverse-Compton scattering of cosmic microwave background (CMB) photons by radio-emitting electrons in a highly relativistic jet. However, recent data prefer synchrotron radiation by a second distinct electron population as the origin of the HE component. We anticipate that optical polarimetry with Hubble will establish the synchrotron nature of the HE component. Gamma-ray observations with GLAST (renamed as the Fermi Gamma-ray Space Telescope), as well as future TeV observations, are expected to place important constraints on the jet models.

scholarly journals Opacities for photon splitting and pair creation in neutron star magnetospheres

2019 ◽  
Vol 486 (3) ◽  
pp. 3327-3349 ◽  
Author(s):  
Kun Hu ◽  
Matthew G Baring ◽  
Zorawar Wadiasingh ◽  
Alice K Harding
Keyword(s):  
High Energy ◽  
Pair Creation ◽  
X Rays ◽  
Static Vacuum ◽  
Curved Space ◽  
X Ray ◽  
Inverse Compton Scattering ◽  
Inverse Compton ◽  
Photon Splitting ◽  
Magnetic Pair

ABSTRACT Over the last four decades, persistent and flaring emission of magnetars observed by various telescopes has provided us with a suite of light curves and spectra in soft and hard X-rays, with no emission yet detected above around 1 MeV. Attenuation of such high-energy photons by magnetic pair creation and photon splitting is expected to be active in the magnetospheres of magnetars, possibly accounting for the paucity of gamma-rays in their signals. This paper explores polarization-dependent opacities for these two QED processes in static vacuum dipole magnetospheres of highly magnetized neutron stars, calculating attenuation lengths and determining escape energies, which are the maximum photon energies for transparency out to infinity. The numerical trajectory integral analysis in flat and curved space–times provides upper bounds of a few MeV or less to the visible energies for magnetars for locales proximate to the stellar surface. Photon splitting opacity alone puts constraints on the possible emission locales in their magnetospheres: regions within field loops of maximum altitudes $\, r_{{\rm max}}\sim 2\!-\!4\,$ stellar radii are not commensurate with maximum detected energies of around 250 keV. These constraints apply not only to magnetar flares but also to their quiescent hard X-ray tail emission. An exploration of photon splitting attenuation in the context of a resonant inverse Compton scattering model for the hard X-ray tails derives distinctive phase-resolved spectroscopic and polarimetric signatures, of significant interest for future MeV-band missions such as AMEGO and e-ASTROGAM.

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